Ecology, Population Dynamics, and Translocation of the Endangered Laysan Teal

Science Center Objects

The Laysan teal has the most restricted range of any duck species and is especially vulnerable to extinction because of its small population size and vulnerability to climate change. The species was believed to be endemic to one island until new sub-fossil evidence and ancient DNA-testing revealed Laysan teal were widespread across the Hawaiian archipelago. Despite its previously wide distribution, today the Laysan teal shows strong tenacity to Laysan Island in the Hawaiian Islands National Wildlife Refuge (NWR) that is a part of the Papahānaumokuākea Marine National Monument. Small isolated populations are extremely vulnerable to extinction from stochastic events, natural disturbance, alien species, emerging diseases, and sea-level rise. On Laysan Island, the endemic rail, honeycreeper, and millerbird all went extinct after the introduction of rabbits to this fragile ecosystem. 

Laysan ducks on Midway Atoll
Male and female pair of Laysan ducks at Midway Atoll National Wildlife Refuge. Photo: J. Klavitter

Overview:

Cooperators carry Laysan ducks across the beach in translocation from Midway Atoll to Kure Atoll
Cooperators from state, federal, and non-profit organizations carry translocated Laysan teal across the beach on Kure Atoll. Photo: N. Worster

The Laysan teal (Anas laysanensis) has the most restricted range of any duck species and is especially vulnerable to extinction because of its small population size and vulnerability to climate change. The species was believed to be endemic to one island until new sub-fossil evidence and ancient DNA-testing revealed Laysan teal were widespread across the Hawaiian archipelago. Despite its previously wide distribution, today the Laysan teal shows strong tenacity to Laysan Island in the Northwestern Hawaiian Islands (NWHI) that is part of the Papahānaumokuākea Marine National Monument. Small isolated populations are extremely vulnerable to extinction from stochastic events, natural disturbance, alien species, emerging diseases, and sea-level rise. On Laysan Island, the endemic rail, honeycreeper, and millerbird all went extinct after the introduction of rabbits to this fragile ecosystem. The last wild population of Laysan teal existed as a relict population with a limited carrying capacity and vulnerable to population crashes during drought and epizootics. Wild translocation or the movement of wild birds to establish additional populations is a high priority of the U.S. Fish and Wildlife Service to reduce the species high extinction risks and recover the species. Due to the remoteness of Laysan Island, few researchers or naturalists have studied the species and little was known of its ecology or population status. Refuge managers are interested in restoring ecosystems of the Northwestern Hawaiian Islands; however, little was known about the Laysan teal’s habitat use or requirements. This project examined aspects of the Laysan teal ecology including population dynamics and reintroduced biology, behavior, reproductive success, population genetics, and habitat use on Laysan Island and the reintroduced population on Midway Atoll NWR.

Application of USGS research to restore a second population of the species has been viewed as one of the most successful applied research/conservation projects in decades. This work has been a model for recent FWS efforts for other reintroductions in the Hawaiian Islands (i.e. Nihoa millerbird translocations) and demonstrated that additional populations can be created.

Additional studies were added to help the USFWS develop techniques monitor the birds reproduction and survival, identify population crashes, identify causes of population crashes, and predict the impacts of climate change on the species. Impacts from the 2011 Tohohu tsunami on the population were also examined for our USFWS partners. Additionally, analysis of genetic variability in the species was conducted to better understand the evolutionary potential of the species.

Project Objectives:

The objectives of this study were to investigate factors essential to conservation and management of the Laysan teal:

Cooperators measure and process Laysan ducks
A frenzy of activity, hydrating, weighing and measuring translocated Laysan teal. Photo: E. Dale, USFWS
  1. Population Dynamics - Identify factors influencing reproduction and mortality on Laysan Island. Develop population models to estimate population size, age, and sex structure and population viability. Determine survival, reproductive status using appropriate models.
  2. Ecology - Examine behavioral ecology, foraging, wetland use in relation to invertebrate prey densities, prey and habitat availability, and environmental parameters influencing prey and habitat use by Laysan teal.
  3. Translocation - Apply data gathered on foraging ecology, population dynamics, habitat use, and behavior to make recommendation on best methods, timing,  and ecosystem restoration required for the highest probability of a successful translocation and population persistence.

Highlights and Key Findings:

An experimental translocation of Laysan teal from Laysan Island to Midway Atoll NWR was conducted in 2004 and 2005 in collaboration with the USFWS. The 2004 and 2005 experimental reintroduction of 42 birds was successful and won a Recovery Leader Award from the USFWS. The methods and results have been published in books, journals, and reports and have been featured as models and examples for species recovery, adaptive management, and research.

USGS provided technical support and design for the 2014 translocation of Laysan teal from Midway Atoll NWR to Kure Atoll in partnership with the US Coast Guard and the State of Hawai‘i Division of Land and Natural Resources.